Aluminium alloy



Patented May 29, 1934 PATENT OFFICE 1,960,916 ALUMINIUM ALLOY AlfredJohn Murphy and Stanley Alfred Edward Wells, Teddington, England,assignors to J.

' Stone & Company Limited, Deptford, England,

a corporation of Great Britain i No Drawing. Application June 14, 1933,Serial No. 675,866. In Great Britain June 29, 1932 2 Claims.

This invention comprises improvements in aluminium alloys and inparticular aluminium alloys of the class containing copper, nickel,magnesium, iron and silicon.

The object of the invention is to produce an alloy of this class havingits grain refined, possessing improved running and casting qualities,having high mechanical strength capable of being' enhanced byappropriate heat treatment, and, without detriment to any of thesecharacteristics, having a capacity for carrying a high iron content.

According to this invention, cerium is added to an aluminium alloy ofthe class referred to, the alloy thereby being cleansed and acquiringthe properties referred to and being enabled to carry an iron contentwhich is added to it in predetermined proportion and in accordance withthe value of the cerium addition. The alloy has particularlyadvantageous casting qualities. It may be submitted to appropriate highand/or low temperature treatment, the final product being highlycleansed and possessing a refined grain and high mechanical strength.Certain micrographical constituents which make for structural weakness,are reduced by the addition of cerium, as compared with the resultsobtained when other metals are employed for a similar purpose. Theapproximate ranges of composition 01. the alloys in which we havediscovered that these beneficial effects are exhibited are as follows:

According to one practical process in accordance with theseimprovements, an alloy is made up as Iollowsz-Ferro-aluminium,containing 10 per cent iron, is added to molten aluminium in the desiredproportion. The following are then added in succession and in theproportions required to give the desired compositionzcerium-iron-aluminium alloy containing 5 per cent cerium, 10 per centiron and 85 per cent aluminium; nickel-aluminium alloy containing 20 percent nickel; copper-aluminium alloy containing 50 per cent copper;silicon-aluminium alloy containing 12 per cent silicon, and, finallymagnesium. Alternatively, the cerium may be added as the pure metal, oras an alloy with any of the other components of the final alloy. Thesequence of additions may also be altered from the above. a

The subsequent treatment for enhancing the mechanical properties of thealloys may be carried out by quenching or rapidly cooling them from atemperature of 480 C. to 570 C. followed by ageing at a temperature notexceeding 300 C. Thus the treatment may be carried out in two stages.The'first, for a period of four hours at 560 C. and the second for aperiod of sixteen hours at 200 C. These periods and temperatures havebeen found suitable for ordinary purposes but they may be varied so asto give other combinations of high and low temperatures and periods oftreatment. Alternatively, the alloys may be aged at a temperature notexceeding 300 0. without previous treatment at higher temperatures aftercasting.

It will be understood that the cerium addition is the importantconsideration for the purpose described. In some alloys, manganese,chromium and titanium may be introduced in predetermined proportions asfurther additions but not as substitutes for the cerium.

It is desirable to increase the cerium content as the iron content isincreased and the duration of the first heat treatment stage may beincreased as the iron content is increased, the said period alsovarying,'of course, with the type of microstructure desired. I

Within the general limits above indicated some alloys are preferred forcastings and others for forgings. This will be seen from the followingexamples:-

Remainder.

Another advantage obtained when using cerium, as compared with a metalsuch as titanium, is that the melting point is lower so that the makingupof the alloy is facilitated.

We claim:-

1. An aluminium alloy containing 0.5 to 5.0 per cent copper, 0.5 to 3.0per cent nickel, 0.1 to 2.5

per cent magnesium, 0.2 to 2.5 per cent silicon, 0.2 to 2.0 per centiron, 0.02 to 1.0 per cent cerium, and the balance substantially allaluminium.

2. An aluminium alloy containing 0.5 to 5.0

mium and manganese for imparting the characteristics of resistingcorrosion and increasing hardness, in the proportions of 0.02 to 0.20per cent chromium and 0.1 to 0.5 per cent mangaper cent copper, 0.5 to3.0 per cent nickel, 0.1 to nese, and the balance substantially allaluminium.

ALFRED JOHN MURPHY. STANLEY ALFRED EDWARD WELLS.

